In the case of motor vehicles, especially or tractortrailer units all lubricating points both on the tractor as well as on the trailer are supplied with lubricant from one supply pump, customarily located on the tractor. Whenever a customary progressive lubricating system with series connected distributors or distributor pistons is used for this purpose, then lubrication pipe transfers from the tractor to the trailer are needed in a number which corresponds to the number of the lubricant distributors on the trailer. In case of the progressive lubrication system, the passage of lubricant of all pipes is blocked in case one lubrication pipe is locked. Depending on the design the trailer nowadays contains one, two or more lubricant distributors.
The object of the present invention is to provide a multiple coupling of the type which may be used for connection of trailers with variable numbers of lubrication points in the trailer, i.e., which permits the connection of trailers with variable members of lubrication points, with the same tractor.
This task is solved according to the invention by providing a plug box connected to a source of lubricant under pressure and at least two outlets, a plug in piece which has at least two inlets corresponding to the outlets of the plug boxes and at least two passages to remote lubrication points corresponding to the number of remote lubricant distributors. A connecting passageway between the inlet of the plug box and the passage to the remote lubrication point of the plug in piece, always one value arrangement is provided which selectively opens one of the passages of the lubricant from the plug in piece, or (2) to a return of the plug box. The principle of solution is that multiple coupling will just always open as many lubrication passages, as there are lubrication points or lubrication distributors in the trailer, while the lubricant of the blocked coupling passages is returned to the supply pump. If, therefore one has for example a multiple coupling with three possible passages, but the trailer has only two lubrication points or lubricant distributors, then one passage is closed with the valve arrangement provided according to the invention and the latter is coupled with the return to the supply pump. One proceeds correspondingly, with two of the passages, whenever a trailer with for example only one lubrication point or one lubricant distributor is to be connected with the tractor with a multiple coupling which has three possible passages.
An easily constructed and particularly simple development of the valve arrangement in which the valve arrangement has a double piston arrangement which in a first terminal position closes the passage from the pertinent plug box inlet to the pertinent plug-in piece passage to the remote lubrication point, and opens the passage from the pertinent plug box inlet to the return, and in its other terminal position inversely opens the passage from the pertinent plug box inlet to the pertinent plug in piece passage to the remote lubrication point and closes the passage from the pertinent plug box inlet to the return. This will guarantee--while functioning securely--that either a flow through to the one or several lubrication point(s) or the one or several lubricant distributor(s) in the trailer or a return of the lubricant to the supply pump, is possible. The double piston arrangement has two pistons mutually supported by means of a first spring with outward-facing sealing surfaces, which pistons are pressed jointly by a second spring in the direction of the first terminal position.
Furthermore, the double piston arrangement is disposed in a chamber which forms at its terminal surfaces the sealing seats for the sealing surface of the pistons whereby the inlet of the plug box is connected by way of the connecting pipe with the chamber between the two sealing seats and whereby the connecting pipe starts from the one terminal surface of the chamber to the escape passages to the remote lubrication distributor point of the plug-in piece and the return starts from the other terminal surface of the chamber. This structure has the advantage of providing a simple insertion of the valve arrangement into the plug box.
This double piston arrangement is shiftable by means of a rod insertable into the connecting pipe, during the plugging together of plug box and plug-in piece counter to the pressure of the second spring from the first terminal position into the second terminal position. In this way the selection of the open or closed connecting pipes by insertion or removal of corresponding rods into the plug-in piece, which is to be assigned to a trailer with a corresponding number of lubrication points, is possible.
Thus, one and the same multiple coupling may be adapted by insertion of one or several pegs into the plug-in piece to the corresponding number of lubrication points or lubricant distributors of the trailer without any constructional changes. The one piston of the double piston arrangement guaranteeing the closing of the passage from the plug box inlet to the outlet passage to the remote lubrication points of the plug-in piece, projects with an extension--on which a pin may act--into the connecting pipe or passage to thus provide a particularly simple and forced action of the rods on the valve arrangement in the plug box is guaranteed.
The pistons of the double piston arrangement always have extensions facing each other, on which the first spring is seated so the pistons of the double piston arrangement are kept in the required alignment for the reciprocal movement in the chamber. The other piston guaranteeing the closing of the passage from the inlet of the plug box to the return, carries an outside extension on which the second spring is disposed. This arrangement guaranties the cantfree guidance of the piston arrangement in the chamber and of the position extension in the connecting pipe or passageway.
These casings serve for the firm plugging in of the plug-in piece into the plug box and they additionally guarantee the support always of the rods used as well as the guiding of the piston extension. Also, non return valves have been provided in the outlet passages to the remote distribution points of the plug in pieces as that during pulling out of the plug-in piece from the plug-in box the lubricant would not flow out of the lubrication pipes of the trailer.
Finally, plug-box and plug-in piece may be releaseably coupled with one another by means of a hand-operated threaded connection which guarantee the firm but releasable coupling of the plug-in piece with the plug box.